#include <bits/stdc++.h>

#define eb emplace_back
#define ep emplace
#define fi first
#define se second
#define in read<int>()
#define lin read<ll>()
#define rep(i, x, y) for(int i = (x); i <= (y); i++)
#define per(i, x, y) for(int i = (x); i >= (y); i--)

using namespace std;

using ll = long long;
using db = double;
using pii = pair < int, int >;
using vec = vector < int >;
using veg = vector < pii >;

template < typename T > T read() {
	T x = 0; bool f = 0; char ch = getchar();
	while(!isdigit(ch)) f |= ch == '-', ch = getchar();
	while(isdigit(ch)) x = x * 10 + (ch ^ 48), ch = getchar();
	return f ? -x : x;
}

template < typename T > void chkmax(T &x, const T &y) { x = x > y ? x : y; }
template < typename T > void chkmin(T &x, const T &y) { x = x < y ? x : y; }

const int N = 1e6 + 10;
const db eps = 5e-8;

db a;

db f(db x) { return pow(x, a / x - x); }

db simpson(db l, db r) { return (r - l) / 6 * (f(l) + f(r) + 4 * f((l + r) / 2)); }

db calc(db l, db r, db eps) {  
	db mid = (l + r) / 2, lt = simpson(l, mid), rt = simpson(mid, r), ct = simpson(l, r);
	if(fabs(lt + rt - ct) <= 15 * eps) return (lt + rt - ct) / 15 + lt + rt;
	else return calc(l, mid, eps / 2) + calc(mid, r, eps / 2);
}

int main() {
#ifdef YJR_2333_TEST
	freopen("1.in", "r", stdin);
#endif
	cin >> a; if(a < 0) puts("orz"); else printf("%.5lf\n", calc(eps, 20, eps)); return 0;
}
